Method of making a commutator



P S, 1949. R. s. JENKINS 2,466,432

METHOD OF MAKING A COMMUTA'IOR Original Filed Oct. 11, 1946 Fig.1. 2

Fig.2.

Inventor: -4 Robert S. Jenkins,

His Attorneg Patented Apr. 5, i949 I METHOD DEMAKING A COMMUTATOR RobertS. Jenkins, Lansing, Mich., assignor to General Electric Company, acorporation of New York I 7 Original application October 11, 1946,Serial No. 702,705. Divided and this application January 22, 1948,Serial No. 3,800 7 2 Claims. (Cl. 29-15554) My invention relates to animproved method of making commutators for dynamoelectric machines.

An object of my invention is to provide an improved method of making acommutator.

Further objects and advantages of my invention will become apparent andmy invention will be better understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming part of this specification.

This application is a division of my application Serial No. 702,705,filed October 11, 1946, and

assigned to the assignee of the present appli-- cation.

In the drawing, Fig.'1 is an end elevational view of a commutatorincluding an embodiment of my invention: Fig. 2 is a sectional viewtaken along line 22 of Fig. 1; Fig. 3 illustrates a step in the methodof making my improved commue tator; Fig. 4 is a perspective view of anassembled hub and separators used in making my improved commutator priorto the formation of commutator segments between the separators thereof;

and Fig. 5.is a plan view partly broken away of the arrangement shown inFig. 3.

Referring to the drawing, I have illustrated one embodiment and a methodof making this embodiment of my invention in which I form a commutatorprovided with a hub and separators for the commutator segments, all ofwhich are formed of electrically conductive material and in which thecommutator segments are insulated from the supporting hub and separatorsby a suitable insulation, such as a. fused vitreous enamel insulationcoating applied over the surfaces of the segment supporting andseparating structure. In making such a commutator, a substantiallycylindrical metal hub I of steel or other suitable material adapted formounting on a supporting shaft is provided and a plurality of outwardlyextending separators is secured to the outer cylindrical surface of thehub I. These separators may be formed as shown in the drawing comprisingsubstantially U-section irregular or corrugated separator units 2 whichare secured to the supporting hub I by the bases thereof arranged incontact with the outer surface of the hub I and secured by spot welding,brazing,

. or other suitable fused connection between the base of the separatorand the hub I or by any other suitable means, as by bolts, screws, orrivets. This provides a construction as shown in Fig. 4 in which aplurality of outwardly extending irregular separators extendsubstantially radially outwardly from the central hub member I. Ifdesired, each of these separators can bemade as an individual unitindividually secured to the hub; however, this would be a more expensiveand complicated arrangement than that shown in Fig. 4. This assembly ofhub and separators then is completely insulated by the application of acoating of suitable insulating material, such as a fused vitreousenamel'insflation over the exposed surfaces of the separators 2 and ofthe exposed peripheral surfaces of the hub I. sulation coating beapplied over all of these surfaces and that no surface oitheelectrically conductive separators or hubs remain exposed, as such anuncovered portion of either of these members would form' a ground orshort circuit for a commutator segment in contact therewith.

After the assembly of separators and hub has been completed, thisassembly is arranged in a mold as shown in Figs. 3 and 5 with theseparators 2 arranged in the mold in alignment with inwardly extendingprojections 3 formed on the inner surface of a mold 4, after whichcommu-' tator segments of suitable electrically conductive material aremolded between all of theseparator 1 members 2. In Fig. 3, I have shownone step in the method of molding such commutator segments whichincludes the provision of intimately molded powdered electricallyconductive'material 5 supplied between the separator members 2 by anysuitable means, as through a supply nozale 6 and a supply regulatingvalve I, such that the powdered electrically conductive material isarranged in intimate engagement-with the insulation on the separatormembers 2 andis thoroughly'. compacted therebetween and between the moldprojections 3 and the outer surface of the mold. When all of the spacesbetween the separator members 3 have been filled with electricallyconductive material, the mold l with the commutator members thusassembled therein is placed in a suitable furnace, and the temperatureis raised and held at such a value as to sinter the molded powderedelectrically conductive material 5 to form substantially solidcommutator segments thereof. After this sintering operation, thecompleted commutator is allowed to cool as desired, and the assembledcommutator segments, separators, and hub are removed from the mold 4 andform a commutator as shown in Figs. 1 and 2. In' such a commutator, thesegments are formed as solid members 8 insulated It is extremelyimportant that this in- 3 from each other and from their supportingstructure by the insulation on this structure and by air gaps 9 betweenradially outwardly extending portions at the ends of the commutatorsegments of a predetermined desired length which have been formed by themold projections I during the molding and sintering process. Thisprovides a completed commutator with an undercut separator arrangementbetween the outer ends of the commutator segments to provide for apredetermined amount of wear of the commutator segments before itis'necessary to make any repairs, thereto.

The irregular separators 2 preferably are formed as shown in theillustration with the corrugations or irregular ribs thereon extendingaxially of these separator members, as this provides for a secureanchoring of the commutator segments to the hub member, but thisirregular surface could take any desired shape which would providesuitable anchoring for the molded commutator segments to the supportinghub. Furthermore, any suitable molding operation for the formation ofthe commutator segments could be utilized where a suitable insulation isprovided over the separators and the exposed surfaces of the supportinghub which would not be destroyed during the molding operation. A fusedvitreous enamel would be suitable for this purpose as the meltingtemperature thereof would be considerably higher than the molding andsintering temperatures of the commutator segments if these were to bemade of copper or similar electrically conductive material.

While I have illustrated and described a particular method of myinvention, modifications thereof will occur to those skilled in the art.I desire it to be understood, therefore, that my invention is not to belimited to the particular method disclosed, and I intend in the appendedclaims to cover all modifications which do not depart from the spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

- the mold.

i. A method of making a commutator comprising forming a supporting hub,securing a plurality of outwardly extending separators having irregularsurfaces to the outer periphery of the hub. coating the exposed surfacesof the separators and the exposed peripheral surfaces of the hub withinsulation, arranging the assembled hub and separators in a mold withthe separators arranged in alignment with inwardly extending projectionson the mold, molding powdered electrically conductive material betweenadjacent sides of the separators and the mold projections, sintering themolded powdered material to form substantially solid commutator segmentsthereof, and removing the assembled commutator from the mold.

2. A method of making a commutator comprising forming a substantiallycylindrical metal supporting hub, securing a plurality of substantiallyU-section corrugated metal separatorsby fusing the bases thereof to theouter periphery of the hub. coating the exposed surfaces of theseparators and the exposed peripheral surfaces ofthe hub with a fusedvitreous enamel insulation, arranging the assembled hub and separatorsin a mold with the separators arranged in alignment with inwardlyextending projections on the mold, molding powdered electricallyconductive material between adjacent sides of the separators and themold projections in intimate engagement with the enamel insulation,sintering the molded powdered material to form substantially solidcommutator segments thereof, and removing the assembled commutator fromROBERT s. JENKINS.

REFERENCES CITED UNITED STATES PATENTS Name Date Horlacher Oct. 16, 1945Number

